Frame structure for the upper crank case of dual-shaft internal combustion engines of the opposed piston type



June 1957 J. E. JOHANSSON 2,796,857 FRAME STRUCTURE FOR THE UPPER CRANK CASE OF DUAL-SHAFT- INTERNAL. COMBUSTION mamas OF THE OPBOSED PISTON TYPE Filed April 18, 1955 2 Sheets-Sheet l lllll INVENTOR.

June 1957 J E- JOHANSSON 96,857

FRAME STRUCTURE FOE THE UPPER CRANK CASE OF DUALSHAFT INTERNAL COMBUSTION ENGINES OF THE OPPOSED PISTON TYPE Filed April 18, 1.955 2 Sheets-Sheet 2 IINVENTOR ATTORNEYS FRAME STRUCTURE FOR THE UPPER CRANK CASE OF DUAL-SHAFT INTERNAL COMBUS- %N ENGINES OF THE OPPOSED PISTON Johan Erik Johansson, Goteborg, Sweden, assignor to Aktieholaget Gitaverken, Goteborg, Sweden, :1 corporation of Sweden Application April 18, 1955, Serial No. 502,138

Claims priority, application Sweden April 28, 1954 3 Claims. (Cl. 123-195) In dual-shaft internal combustion engines of the op posed piston type, the frame is bolted to a base near the lower crank case, and the forces acting on said crank case can be directly transmitted to the base. The upper crank case which is connected to the base by means of the intermediate parts of the frame and the lower crank case, is likely to be subject to deformations or vibrations on account of the bending or torsional forces acting there- On, especially in multi-cylinder engines.

In conventional constructions, the crank shaft bearing beams which form part of the crank case, are devised in such a manner that their main portion is connected with the upper part of the crank shaft bearing pedestal near the plane of division of the hearing. In many cases, the crank shaft is located at a lower level than the plane of division of the crank case. As a result thereof, the transverse beam is considerably weakened. Consequently, a considerable part of the forces acting between the longitudinally extending lateral sides of the crank case has to be transmitt d through the bearing caps. For practical purposes the transverse joint has to be considered as entirely interrupted. Consequently, the beams which constitute the sides of the crank case have to be dimensioned as though they were independent of each other.

The object of this invention is to increase the rigidity at the upper part of the frame so that considering, for instance, the bending stresses in a horizontal plane, the crank case can be considered as a frame structure having parallel upper and lower frames and interconnecting bars, in which the frames can be devised with smaller dimensions than in conventional constructions.

In the accompanying drawing there is illustrated, by way of example, part of the frame of an opposed piston internal combustion engine according to the invention. Fig. 1 is a cross-sectional view of the upper part of the frame and Fig. 2 an appertaining top view. Fig. 3 is a cross-sectional view of my invention showing the upper crank shaft and upper crank case half detachably connected to the lower fixed part.

In an engine of the type ref rred to, the frame may comprise two supporting members or uprights arranged between each two adiacent cylinders and connected at their upper and lower ends by means of trough-shaped beams which form part of the crank cases of the engine. Fig. 1 shows part of the upper end of such a frame. The vertical supporting members between the various cylinders consist of two tubular uprights 1 which at the central part of the frame are interconnected by suitable reinforcing members 2, and at their upper and lower ends are interconnected by substantially identical crank case portions. Each crank case portion comprises a longitudinally extending trough-shaped beam 3 and lateral beams 4 and 5. The ends of the tubular members are interconnected by a moulding 6 including a pedestal body 7 and ribs 8 and 9 which project from a central web and constitute reinforcing members. I

At the upper crank case there are provided webs 10 9 5 Patented June 25, 1957 ice integral with the lateral beams 4 and 5 and projecting inwardly towards the central part of the engine. The last named webs are sloping such as to be in alignment with the ribs 8 of the moulding and extend to said ribs.

The various parts of the crank case half are welded to each other so as to constitute a unitary structure in which the webs projecting from the lateral beams together with the various parts of the crank shaft bearing constitute transverse beams comprising a reinforced joint which extends in an unbroken continuous course between the lateral beams.

An additional increase of the rigidity in the transverse direction is obtained by reinforcing members 11 which are T-shaped in cross-section and inserted between the lateral beams and the moulding. The web of each member 11 is wedge-shaped in conformity with the slope of the appertaining web 10. The members 11 fill up the spaces on the outer sides of the moulding and are welded to the lateral beams, the transverse beam and to the projecting webs 10.

The webs 10 which form part of the transverse crank shaft bearing beams merge into adjacent webs on the same side of the crank case along a-rcuate lines having a slightly greater radius than the pistons of the engine. The recess formed in this way between adjacent crank shaft bearing beams is dimensioned such that a piston the configuration of which is shown by dotted lines 12 in Fig. 2 can be introduced between the crank shaft mounted in its bearings and any of the lateral beams 4 or 5.

The above described embodiment is shown by way of example only and the details thereof may be modified in various manners within the scope of the appending claims.

The portion of the crank shaft bearing beam'which directly supports the bearing pedestal and interconnects the ends of the tubular uprights may consist of cast steel or a die-formed or welded piece which may form a larger part of the transverse beam than according to the drawing and may even extend to the outer sides of the engine and form part of the longitudinally extending beams.

As shown in Fig. 3 the upper half 13 of the upper crank may be detachably secured to the fixed lower part by suitable bolt means to clamp the crank shaft 14 between the upper and lower crank shaft bearings.

What I claim is:

1. In a two-shaft internal combustion engine of the opposed piston type, an upper crank shaft, an upper crank case divided in a horizontal plane substantially at the level of the axis of the crank shaft into a detachable part and a fixed part containing the upper crank shaft bearings, longitudinally extending beams constituting horizontal m'arg'in parts of the fixed crank case part, a plurality of transverse beams each carrying a crank shaft hearing and arranged with their upper margins in the plane of divisioninterconnect-ing said margin beams, said transverse beams comprising :a central web and lateral ribs projecting therefrom, said lateral ribs forming a continuous strain band between said margin beams running in an arched curve immediately below the associated bearing.

2. In a two-shaft internal combustion engine of the opposed piston type, an upper crank shaft, an upper crank case divided in a horizontal plane substantially at the level of the axis of the crank shaft into a detachable part and a fixed part containing the upper crank shaft bearings, longitudinally extending beams constituting horizontal margin parts of the fixed crankcase part, a plurality of transverse beams each carrying a crank shaft bearing and interconnecting said margin beams, said transverse beams comprising a bearing saddle having a central web and slightly arched lateral ribs projecting therefrom below said bearing, lateral webs projecting inwards and downwards from said horizontal margin beams, said lateral webs and said lateral ribs being united to form a continuous strain hand between the margin beams, and reinforcing members inserted between said bearing saddle, said margin beams and said Ilateral Webs, said reinforcing members connecting the margin beams and the upper part of the bearing saddle in the plane of division.

3. In a two-shaft internal combustion engine of the opposed piston type, an upper crank shaft, an upper crank case divided in a horizontal plane substantially at the level of the axis of the crank shaft into a detachable part and a fixed part containing the upper crank shaft bearings. longitudinally extending beams constituting horizontal margin parts of the fixed crank case part, 'a plurality of transverse beams each carrying a crank shaft bearing and interconnecting said margin beams, said transverse beams comprising a bearing saddle having a central web and lateral ribs projecting therefrom below saidvbearfing, lateral webs projecting inwards from said horizontal margin beams, said lateral Webs and said lateral ribs being united to form a continuous strain band between the margin beams, and adjacent lateral webs merging into each other along an arcuate line having a slightly greater radius than the engine piston-s, whereby insertion of a piston between the crank shaft mounted in its bearings and any of said beams is permitted.

References Cited in the file of this patent UNITED STATES PATENTS 2,245,810 Owens June 17, 1941 2,246,857 Owen-s et al June 24, 1941 2,416,045 Ch'aprnan Feb. 18, 1947 2,486,927 Chapman et a1 Nov. 1, 1949 

